Genetic disruption of Syk expression in human NHL cell lines. Syk expression was disrupted in human BL cell lines. (A) Semiquantitative Western blot analysis of Syk knockdown in BJAB cells with anti-Syk (top panel); blots were then stripped and reprobed with anti–β-actin (bottom panel). Cells were infected with empty vector (pLL3.7), control shRNA (shLuc), or Syk-specific shRNA (shSyk). Percent knockdown was determined by densitometry of the Syk bands relative to the β-actin bands. (B) Plot of in vitro tumor competition assay in RAJI and BJAB cells infected with either control shLuc or shhSyk, as described in Figure 4 (n = 4).